Apparatus and method for depositing electronically conductive pasting material

ABSTRACT

A method and apparatus are described for reducing particle contamination in a plasma processing chamber. In one embodiment, a pasting disk is provided which includes a disk-shaped base of high-resistivity material that has an electrically conductive pasting material layer applied to a top surface of the base so that the pasting material layer partially covers the top surface of the base. The pasting disk is sputter etched to deposit conductive pasting material over a wide area on the interior surfaces of a plasma processing chamber while minimizing deposition on dielectric components that are used to optimize the sputter etch process during substrate processing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 11/947,459, entitled “Apparatus and Method for DepositingElectrically Conductive Pasting Material”, filed Nov. 29, 2007, which isherein incorporated by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

Embodiments of the present invention generally relate to substrateprocessing systems and chambers used to process semiconductor wafers,solar panels, and flat panel displays and, in particular, to depositingelectrically conductive pasting material in a plasma processing chamber.

Description of the Related Art

To help ensure semiconductor device integrity and performance, asemiconductor substrate is often cleaned prior to depositing a film onthe substrate to remove contaminants and native oxides which may resideon the substrate surface. Conventional preclean processes typicallyinclude a sputter etch process to remove the contaminants and expose thenative oxides. The native oxides may then be removed by additionalsputter etching and/or reactive etching which uses a reduction reaction.

One example of a native oxide is silicon oxide which tends to form onthe surface of a silicon substrate or film. The native silicon oxidelayer is a thin layer (e.g., about 30 angstroms thick) that forms whenthe silicon substrate is exposed to oxygen. Oxygen exposure may occurwhen moving the substrate between processing chambers at atmosphericconditions, or if oxygen remains in a vacuum processing chamber andcontacts the substrate. Prior to a metallization process, it is oftendesirable to remove the native silicon oxide layer on silicon surfacesin order to lower the contact resistance between the metal layer andunderlying silicon material.

Sputter etching is often used to remove the native silicon oxide layeron the surface of a silicon film/substrate before depositing a metallayer which, for example, may be deposited by sputter deposition orchemical vapor deposition. The sputter etching process is typicallyperformed in a vacuum plasma etch chamber. An inert gas, such as argon,is used to form a plasma which may be inductively or capacitivelycoupled and which ionizes the gas to produce positively charged ions.The substrate rests on a substrate support near the plasma region andthe substrate support is coupled to a power supply, such as a radiofrequency generator, to bias the substrate support so that the ions areaccelerated towards the substrate surface. The ions strike the substratesurface and the impact ejects the silicon oxide from the substratesurface. The ejected or sputtered material is typically exhausted fromthe vacuum chamber but some may deposit onto the wall surfaces andvarious components inside the chamber. Since sputter etching is anon-selective, physical process, the sputtered material may includeother materials which are located at the substrate surface. In thepresent example, silicon in addition to silicon oxide may be sputteredand deposited onto the walls of the sputter etch chamber. Othermaterials may also be deposited on the chamber walls depending on thesputter etch application.

Although most of the sputtered material produced during etching may beexhausted from the sputter etch chamber, the sputtered material whichdeposits inside the chamber tends to build up over time. As thedeposited films grow thicker, stresses may start to build up within thefilms and these internal stresses can cause the films to delaminate andflake off which may result in particle contamination of the substrate.To prevent such contamination, it is necessary to periodically coat thechamber interior with a material, such as a metal, which acts as a“glue” layer to secure the sputtered material and to provide an adherentsurface for additional sputtered material. This process is called“pasting.” The layer of pasting material deposited onto the chambersurfaces is usually a low-stress material and forms a barrier tocracking and flaking between the layers of higher-stress material thatresults during substrate etching.

A sputter etch chamber may be treated with a pasting material byreplacing the substrate with a pasting disk which includes the pastingmaterial. For example, if the desired pasting material is aluminum, thepasting disk may be an aluminum plate similar in size and shape to thesubstrate. The pasting disk may then be placed on the substrate supportand sputter etched to produce a sputtered material which consists ofaluminum and which coats the interior surfaces of the sputter etchchamber. However, the electrically conductive pasting material may alsodeposit on various dielectric chamber components and this deposition mayaffect the dielectric properties of the chamber components and cause achange in the electric field distribution near the substrate duringsubstrate processing. The uniformity of sputter etching across thesurface of the substrate is determined in part by the electric fielddistribution along the substrate surface and so the process ofdepositing conductive pasting material may result in an undesirableshift in the etching process.

Therefore, a need exists for an improved method and apparatus fordepositing an electrically conductive pasting material which does notadversely affect substrate processing and also reduces substrateparticle contamination.

SUMMARY OF THE INVENTION

The present invention generally provides improved methods and apparatusfor depositing pasting material in a plasma processing chamber. Theplasma processing chamber may be adapted for substrate etching,cleaning, or other types of substrate processing.

One embodiment provides a pasting apparatus for the deposition ofpasting material in a plasma processing chamber. The apparatus generallyincludes a pasting disk for use in a plasma processing chamber, and thepasting disk comprises a disk-shaped base of high resistivity materialwith a pasting material layer applied to the top surface of the basesuch that the pasting material layer partially covers the top surface ofthe base, so that an edge exclusion zone is formed on the base which isfree of pasting material.

Another embodiment provides a plasma processing chamber configured fordeposition of a pasting material. The chamber is a vacuum chamber whichencloses a processing volume and includes a substrate support having apedestal, and a pasting disk disposed on the pedestal. The pasting diskis a disk-shaped base made of a high resistivity material with a pastingmaterial layer applied to the top surface of the base such that thepasting material layer partially covers the top surface of the base, sothat an edge exclusion zone is formed on the base which is free ofpasting material.

A method for depositing pasting material in a plasma processing chamberaccording to an embodiment includes the steps of providing a pastingdisk having a pasting material layer and a base, wherein the layerdiameter is selected to be less than the base diameter to reduce pastingmaterial deposition onto a dielectric edge ring while providing pastingcoverage on desired chamber surfaces, transferring the pasting disk froma pasting disk handling device to a substrate support pedestal,positioning the pedestal into a processing position, sputter etching thepasting material layer to deposit pasting material onto processingchamber surfaces, positioning the pedestal to a transfer position, andtransferring the pasting disk from the substrate support pedestal to thepasting disk handling device.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a cross-sectional schematic view of a sputter etch processchamber which may be used to practice the invention according to oneembodiment of the invention.

FIG. 2A is a detailed cross sectional view of the substrate and edgering shown in FIG. 1 when a bias is applied to the substrate.

FIG. 2B is a detailed cross sectional view of the substrate and edgering shown in FIG. 1 during a sputter etch process.

FIG. 3A is a detailed cross sectional view of the pedestal and edge ringshown in FIG. 1 following a pasting process.

FIG. 3B is a detailed cross sectional view of another embodiment of thepedestal and edge ring shown in FIG. 3A following a pasting process.

FIG. 4A is a cross sectional view of a pasting disk according to oneembodiment of the invention.

FIG. 4B is a top view of the pasting disk shown in FIG. 4A according toone embodiment of the invention

FIG. 5A is a cross sectional view of a pasting disk and edge ringaccording to one embodiment of the invention.

FIG. 5B is a cross sectional view of another embodiment of a pastingdisk and edge ring according to the present invention.

FIG. 6 is a cross sectional schematic view of the upper portion of thechamber shown in FIG. 1 according to one embodiment of the invention.

FIG. 7A is a schematic cross sectional top view of another embodiment ofthe chamber shown in FIG. 1.

FIG. 7B is a schematic cross sectional view of the chamber shown in FIG.7A.

FIG. 7C is a schematic cross sectional view of another embodiment of thechamber shown in FIG. 7B.

FIG. 7D is a schematic top view of the edge ring and pasting disk shownin FIG. 7C.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that features of one embodiment may beincorporated in other embodiments without further recitation.

DETAILED DESCRIPTION

Embodiments of the invention described herein generally provide a methodand apparatus for reducing particle contamination in a plasma processingchamber. In particular, a pasting apparatus and process are provided fordepositing electrically conductive pasting material on surfaces andcomponents of a sputter etch processing chamber without adverselyaffecting substrate processing following the pasting process.

FIG. 1 is a cross-sectional schematic view of a sputter etch processchamber which may be used to practice the invention according to oneembodiment of the invention. In another embodiment, other types ofplasma processing chambers may be used to practice the presentinvention. A chamber 100 includes a chamber body 106 covered by a dome104 with top interior surface 122A and sidewall interior surfaces 122Bwhich enclose a processing volume 119. In another embodiment, the dome104 may be designed to have a top interior surface 122C so that acentral portion of the dome 104 is closer to a substrate 101 so that theetch rate near the center of the substrate 101 may be reduced. Thechamber 100 may also include one or more deposition shields 105 withwalls 121 circumscribing various chamber components to prevent unwantedreaction between such components and ionized process material. Domeshields (not shown) may also be located near dome 104 to preventdeposition of sputtered material onto top interior surface 122A andsidewall interior surfaces 122B. The chamber body 106 and dome 104 maybe made of metal, such as aluminum. The chamber 100 is a vacuum chamberand is suitably adapted to maintain sub-atmospheric pressures duringsubstrate processing.

Within the processing volume 119 is disposed a substrate support 124 forsupporting the substrate 101 which may be a semiconductor wafer. Thesubstrate support 124 further comprises a pedestal 107 upon which thesubstrate 101 rests and a support shaft 112 which is coupled to a liftmechanism 113 which provides vertical movement of the substrate support124 between an upper, processing position (as shown in FIG. 1) and alower, transfer position (not shown). A bellows assembly 110 is coupledbetween the substrate support 124 and chamber bottom 126 to provide aflexible seal that allows vertical motion of the substrate support 124while preventing loss of vacuum from within the etch chamber 100. Asubstrate lift 130 includes lift pins 109 mounted on a platform 108connected to a shaft 111 which is coupled to a second lift mechanism 132for raising and lowering the substrate lift 130 so that the substrate101 may be placed on or removed from the pedestal 107. The pedestalincludes thru-holes 120 to receive the lift pins 109. A bellows assembly131 is coupled between the substrate lift 130 and chamber bottom 126 toprovide a flexible seal which maintains chamber vacuum during verticalmotion of the substrate lift 130.

The chamber 100 is coupled to and in fluid communication with a vacuumsystem 114 which includes a throttle valve (not shown) and vacuum pump(not shown) which are used to exhaust the chamber 100. The pressureinside the chamber 100 may be regulated by adjusting the throttle valveand/or vacuum pump. The chamber 100 is also coupled to and in fluidcommunication with a gas supply 118 which may supply one or more processgasses, such as argon, to the etch chamber 100 for etch processing.

To create the desired plasma for sputter etching the substrate 101, thepedestal 107 is coupled to a radio frequency (RF) match 116 and RF powersupply 117. The pedestal 107 may include electrodes (not shown) disposednear the substrate support surface and these electrodes may be coupledto one or more RF matches 116 and one or more RF power supplies 117. Thepedestal 107 functions as an RF cathode which is electrically isolatedfrom the chamber body 106 and dome 104 which are connected to a ground115. Process gas, such as argon, is introduced into the etch chamber 100from gas supply 118 and the gas pressure is adjusted to a preset valuefor plasma ignition. A plasma 102 is ignited in the processing volume119 through capacitive coupling when RF power is delivered to thepedestal 107. The RF match 116 may be adjusted or preset to improve theefficiency of power transfer from the RF power supply 117 to the plasma102. In addition to providing a plasma source, the RF power supply 117also applies a bias to the pedestal 107 so that positively charged ionsin the plasma 102 are accelerated to the surface of the substrate 101and the substrate surface is sputter etched.

The RF power supply 117 may provide power at a frequency of 13.56 MHz,but other frequencies may also be used. In one embodiment, two RFfrequencies may be used to drive the pedestal 107. A lower frequency maybe used to drive the bias and thereby the ion energy and a higherfrequency may be used to drive plasma creation and plasma energy.

The etch uniformity at the substrate 101 surface may depend in part onthe chamber 100 pressure during processing which is preferablymaintained between about 0.5 milliTorr and about 100 milliTorr. Thepressure may be controlled by adjusting the vacuum system 114. Aspreviously noted, etch uniformity is also determined in part by theelectric field distribution near the substrate surface. If the electricfield in nonuniform along the substrate surface, the etch rate will alsotend to be nonuniform along the substrate surface. Nonuniformity of theelectric field may be especially pronounced near the edges of thesubstrate since electric charges tend to concentrate along sharp edgesor radii and this may cause higher etch rates near the edges of thesubstrate. To help mitigate this “edge effect”, an edge ring 103 made ofdielectric material is disposed on the pedestal 107 so that the edgering 103 surrounds the edges of the substrate 101. The edge ring 103 mayblock some of the ion flux during sputter etching and also help producea more uniform electric field near the edge of the substrate 101. Theedge ring 103 may be made of quartz, aluminum oxide, or other dielectricmaterials.

FIG. 2A is a detailed cross sectional view of the substrate 101 and theedge ring 103 shown in FIG. 1 when a bias is applied to the substrate101 by means of the biased pedestal 107. An electric field (E field) isrepresented by electric field lines 201 which are shown near the topsurface 204 of the substrate 101 for a moment in time as a time-varyingbias is provided to the pedestal 107 by the RF power supply 117. Inanother embodiment, the bias may be provided by a DC power supply. Theelectric field as represented by electric field lines 201 may be fairlyuniform over the substrate top surface 204 of the substrate due to afairly uniform charge distribution across the planar surface area of thesubstrate top surface 204. Such uniformity tends to produce parallelelectric field lines 201 which are approximately perpendicular to thesubstrate top surface 204. However, at the substrate edge 202 thesurface area greatly decreases and the charge concentration may increasecausing the electric field lines 201 to converge near the substrate edge202. The convergence of the electric field lines 201 may be especiallypronounced near a corner 211. Although the substrate edge 202 mayactually be rounded (and have no corner), the electric field lines 201may also converge along a surface having a small radius. The placementof the edge ring 103 near the substrate edge 202 may limit or minimizethe electric field line 201 convergence at the substrate edge 202 butmay not entirely eliminate this “edge effect” of the electric fieldlines 201, as shown in FIG. 2A.

FIG. 2B is a detailed cross sectional view of the substrate anddielectric ring shown in FIG. 1 during a sputter etch process.Positively charged ions 207, such as argon ions, for example, areprovided by plasma 102. The biased substrate 101 has electric fieldlines 201 near the substrate top surface 204 and substrate edge 202 (seeFIG. 2A). The positively charged ions 207 are accelerated by theelectric field and move in the direction of the electric field lines201. Away from the substrate edge 202, the electric field may be fairlyuniform and the positively charged ions 207 are accelerated towards thesubstrate top surface 204 in a direction approximately perpendicular tothe substrate top surface 204. For example, a positively charged ion 207moves along an impact trajectory line 203 which is tangent to anelectric field line 201 near the substrate top surface 204 (impactsurface). The positively charged ion 207 impacts with substrate 101 at atop surface 204 at impact point 210A with an impact angle β which may bedefined as the angle between the impact surface and impact trajectoryline 203. In this example, the impact angle β is away from substrateedge 202 and may be approximately 90 degrees. The force of impact ejectsor sputters material from the substrate top surface 204 as indicated bysputtered material 206 which is ejected along an ejection trajectory205. An ejection angle α is defined as the angle between the impacttrajectory line 203 and the ejection trajectory 205 near the impactsurface. The ejection or removal of material due to ion impact is calledsputter etching. The material removal rate or etch rate may depend onmany parameters, such as the mass of the positively charged ion 207, theion density of the plasma 102, and the strength of the electric field,to name a few. The ejection trajectory 205 may be approximated as astraight line or line-of-sight trajectory since the ejected material istypically un-ionized and not affected by the electric field. Thetrajectories of the sputtered material 206 may change directionsfollowing collisions with gas atoms/molecules or ions, but betweencollisions the trajectories may approximate straight lines.

Near the substrate edge 202, some of the electric field lines 201 mayconverge and so some positively charged ions 207 may be acceleratedtowards and impact with the substrate edge 202, as shown in FIG. 2B atimpact point 210B. The impact angle β may typically be less than 90degrees but the ejection angle α may have a wide range of values whichcan cause sputtered material 206 to deposit on nearby surfaces, such astop surface 140A, side-wall surface 140B, and lower surface 140C of theedge ring 103. The surfaces that may receive the most deposition arethose which can intercept ejection trajectories 205 from one or morepossible ion impact points. Deposition may also occur from sputteredmaterial 206 which bounces off multiple chamber surfaces beforedepositing on a surface, but sputtered material 206 which does notbounce off of any intervening surfaces and follows direct, straight lineor line-of-sight trajectories to a receiving surface may contribute themost to deposition on the receiving surface. However, the extent ofdeposition also depends on the stickiness of the sputtered material 206to the receiving surface as well as the exhaust routing of the chambervacuum system 114 which may remove some of the sputtered material beforeit can deposit on a surface.

The edge ring 103 may also prevent some ions from striking surfaces ofthe substrate 101 by blocking ions moving along trajectories that arenot perpendicular to substrate top surface 204 and are directed towardssubstrate edge 202. Referring to FIG. 2B, positively charged ions 207impact the top surface 140A of the edge ring 103 at impact point 210C. Agap 219 may exist between substrate 101 and edge ring 103. As may beappreciated, by narrowing the gap 219 and/or raising the top surface140A relative to substrate top surface 204, the edge ring 103 may blockmore ions and thereby prevent more sputtered material 206 fromdepositing on surfaces of the edge ring 103.

As previously mentioned, sputter etching is often used to remove thenative silicon oxide on a substrate surface. The sputtered material 206in this application is primarily silicon oxide but may also include somesilicon, and these materials may deposit on various surfaces of thechamber 100 such as top and sidewall interior surfaces 122A, 122B andthe surfaces previously mentioned for edge ring 103. Depending on thesputter etch application, other materials may also be deposited on thechamber surfaces.

To prevent the sputtered material 206 from causing possible particlecontamination of the substrate 101, the chamber 100 may be periodicallytreated using a pasting process which coats interior surfaces of thechamber 100 with a pasting material. The pasting material is preferablychosen so that the material adheres well to the components and surfacesinside the chamber 100, otherwise the pasting material itself may be asource of particle contamination. Additionally, the pasting material ispreferably chosen so that the material has low internal stress andadheres well to the sputtered material 206, acts as an adherent layerfor additional sputtered material 206, and prevents delamination andflaking of previously deposited sputtered material 206.

Metallic pasting materials may be desirable in some pasting applicationssince some metals are highly ductile and malleable and tend to have lowinternal stresses. Additionally, many chamber components and surfacesare often made of metal and so may provide good adhesion for varioustypes of metallic pasting materials. The metallic pasting material maybe selected based on the desired properties of the pasting material,such as good adhesion to materials which comprise the surfaces to becoated, and an ability to form pasting material layers which resistdelamination and flaking. As mentioned, the latter property may beprovided by a metallic pasting material that is highly ductile ormalleable and produces pasting material layers with low internalstresses.

FIG. 3A is a detailed cross sectional view of the pedestal 107 and edgering 103 shown in FIG. 1 following a pasting process. The substrate 101has been replaced with a pasting disk 300 used for pasting metallicmaterial onto interior surfaces of the chamber 100. The pasting disk 300may comprise a metal plate which has approximately the same size andshape as the substrate 101 so that the metallic pasting disk 300 may betransferred to and from chamber 100 using a substrate handling robot.The pasting disk 300 may comprise one or more metals and/or metal alloyswhich are desired for the pasting application.

To deposit the metal pasting material onto the interior surfaces of thechamber 100, the pasting disk 300 is sputter etched and sputteredmaterial 206 is ejected from a pasting disk top surface 304 and otherexposed surfaces of the pasting disk 300 in a similar way as describedfor substrate 101 and depicted in FIG. 2B. However, the electricallyconductive pasting disk 300 may have greater charge concentrations neara pasting disk edge 302 as compared to the charge concentrations atsubstrate edge 202 during the sputter etch process, and so there may bea greater tendency for electric field lines 201 to converge at thepasting disk edge 302, and this may increase the sputter etch rate and,thus, the deposition rate of sputtered material 206 onto surfaces nearthe pasting disk edge 302.

Referring to FIG. 3A, the sputtered material 206 may form metal deposits301 on one or more surfaces of the edge ring 103, and the metal deposits301 can build up over time after repeated pasting treatments of chamber100. The metal deposits 301 may form on top surface 140A, side-wallsurface 140B, and lower surface 140C of the edge ring 103. The lowersurface 140C may receive fewer metal deposits 301 since this surface maynot be as exposed to sputtered material 206 as the top surface 140A andside-wall surface 140B of edge ring 103. An outer surface 140D and aninner surface 140E of edge ring 103 may receive little if any sputteredmaterial 206 since these surfaces are not exposed to line-of-sighttrajectories for material ejected from pasting disk 300.

FIG. 3B is a detailed cross sectional view of another embodiment of thepedestal and edge ring shown in FIG. 3A as configured for a pastingprocess. The edge ring 103 which is disposed around the periphery ofpedestal 107 may have different shapes, as indicated by the rectangularcross section shown in FIG. 3B, but one or more surfaces of the edgering 103 will generally be exposed to sputtered material 206 which mayform metal deposits 301 on said surfaces, such as top surface 140A.

The presence of metal deposits 301 on edge ring 103 will tend to alterthe electric field distribution near substrate edge 202 since thesurface conductivity of the edge ring 103 is altered by the metaldeposits 301. Additionally, the metal deposits 301 may change shape andextent following each pasting treatment of chamber 100 and this canproduce unpredictable changes in the electric field distribution nearsubstrate edge 202. To avoid undesirable shifts in the sputter etchprocess, it is therefore desirable to minimize the deposition ofelectrically conductive material onto the edge ring 103.

FIG. 4A is a cross sectional view of a pasting disk according to oneembodiment of the invention. The pasting disk 400 is a composite disk ofmore than one material. The pasting disk 400 comprises a base 402 and apasting material layer 401 which is applied to a top surface 406 of thebase 402. The pasting material layer 401 comprises a pasting materialwhich is electrically conductive. In another embodiment, the pastingmaterial may be non-conductive or electrically insulative. The pastingmaterial layer 401 may be applied by masking the base 402 and depositingthe pasting material using a suitable deposition process, such as arcspraying, sputtering, or other deposition methods which may coat thebase 402 with a pasting material layer 401. In another embodiment, thepasting material layer 401 may comprise a thin sheet or disk of pastingmaterial which is applied to the base 402 using a suitable bondingprocess.

The pasting material layer 401 has a layer top surface 404 which issputter etched during a pasting process. The pasting material layer 401has a layer thickness T₁ measured from layer top surface 404 to base topsurface 406, and the base 402 has a base thickness T₂ measured from basetop surface 406 to base bottom surface 409. The layer thickness T₁ mayrange from about 1 micron (μm) to about 100 microns (μm), and the basethickness T₂ may range from about 0.5 millimeters (mm) to about 5millimeters (mm), but other thickness values may also be used. Thepasting disk 400 has an overall thickness T which is approximately thesum of the individual layer and base thicknesses T₁ and T₂.

FIG. 4B is a top view of the pasting disk 400 shown in FIG. 4A accordingto one embodiment of the invention. The pasting material layer 401 has alayer diameter D₁ measured to a layer edge surface 407, and the base 402has base diameter D₂ measured to a base edge surface 408. The pastingmaterial layer 401 is applied so that an edge exclusion zone 403 havingedge exclusion width 410 is produced which is free of the pastingmaterial. The base diameter D₂ is approximately equal to the sum of thelayer diameter D₁ plus twice the edge exclusion width 410. The layerdiameter D₁ is less than the base diameter D₂, and the layer to basediameter ratio D₁/D₂ may range from about 0.4 to about 0.98. In anotherembodiment, the diameter ratio D₁/D₂ may range from about 0.7 to about0.98. The base diameter D₂ of the pasting disk 400 may range from about200 mm to about 300 mm. In another embodiment, the base diameter D₂ mayexceed 300 mm. In yet another embodiment, the pasting “disk” 400 maycomprise a pasting material layer 401 and base 402 which have othershapes, such as oval, square, rectangular, or other shapes, anddifferent shapes may be combined, such as a square pasting materiallayer 401 on a circular or disk-shaped base 402, for example.

The base 402 may be made of a dielectric or high resistivity materialsuch as quartz, aluminum oxide (Al₂O₃), silicon (e.g., intrinsicsilicon), silicon oxide (e.g., SiO₂), ceramic or other suitable highresistivity materials. The pasting material used for pasting materiallayer 401 may vary depending on the desired pasting application. In oneembodiment, the pasting material layer 401 comprises one or more metalsand/or metal alloys such as aluminum, copper, silver, or gold, forexample. In another embodiment, other electrically conductive materialsmay be used for the pasting material layer 401. In yet anotherembodiment, the pasting material layer 401 may comprise non-conductiveor electrically insulative materials.

FIG. 5A is a cross sectional view of a pasting disk 400 and edge ring103 according to one embodiment of the invention. The pasting disk 400is disposed on pedestal 107 and the pasting disk 400 is sputter etchedduring the pasting process. The pasting material layer 401 has a layerdiameter D_(1A) and the base 402 has a base diameter D_(2A).Electrically conductive pasting material is sputter etched at layer topsurface 404 and may also be sputter etched at layer edge surface 407 ofthe pasting material layer 401. Likewise, dielectric material may besputtered from the base 402 at base top surface 406 and base edgesurface 408. Positively charged ions 207 impact the pasting materiallayer 401 at impact points 510 which are located at or near layer edgesurface 407 and layer top surface 404. Pasting material is ejected fromimpact points 510 and travels in line-of-sight trajectories alongejection trajectories 506 (solid arrows) and blocked ejectiontrajectories 505 (dashed arrows). Pasting material ejected along theblocked ejection trajectories 505 is blocked or intercepted by the base402 and does not deposit on the edge ring 103. Pasting material ejectedalong ejection trajectories 506 is not blocked by the base 402 and thepasting material travels past the edge ring 103 without beingintercepted by any surfaces of the edge ring 103.

The impact points 510 on pasting material layer 401 represent a locus ofpoints on a circle of layer diameter D_(1A) such that for any ion impactlocation on the pasting material layer 401, the ejected pasting materialwill travel along a trajectory which is either intercepted or blocked bybase 402 or travels beyond the base 402 without being intercepted by anysurfaces of the edge ring 103. In other words, values for thegeometrical parameters of the pasting disk 400, such as layer diameterD_(1A), edge exclusion width 410, layer thickness T₁, and base thicknessT₂, may be suitably selected for a specific edge ring 103 geometry sothat no sputtered pasting material which follows a straight line orline-of-sight trajectory will be deposited on any surfaces of the edgering 103. Although some sputtered pasting material may bounce offmultiple chamber 100 surfaces and/or scatter off of gas atoms/moleculesor ions before depositing on the edge ring 103, the elimination orreduction of deposition from pasting material having straight line orline-of-sight trajectories originating from any point on the surface ofpasting material layer 401 may significantly reduce the amount ofpasting material which deposits on edge ring 103.

Referring to FIG. 5A, a limit distance d is measured between the topsurface 140A of edge ring 103 and the base top surface 406. The limitdistance d is the minimum distance needed to prevent ejectiontrajectories 506 from being intercepted by the top surface 140A of edgering 103. Since limit distance d references a feature (top surface 140A)of the edge ring 103, it can be appreciated that the choice of valuesfor the geometrical parameters of the pasting disk 400 are selectedbased, in part, on the locations of various features of the edge ring103 in order to satisfy the condition that little or no depositionoccurs on edge ring 103 for sputtered pasting material which followsline-of-sight trajectories from pasting material layer 401. Thegeometrical parameters of the pasting disk 400 may be selected tominimize the deposition of pasting material on other chamber componentswhich are located near the substrate processing area, and the edge ring103 is just one example of such a component.

Depending on the etch application, some electrically conductive pastingmaterial may be deposited on the edge ring 103 without shifting thesputter etch process beyond acceptable limits, and so the range ofacceptable values for the geometrical parameters of the pasting disk 400may be increased. For example, the deposition of limited amounts ofconductive material at the top surface 140A near outer surface 140D ofedge ring 103 may have minimal effect on the electric field distributionnear the substrate edge 202 and so the sputter etch process may remainwithin acceptable limits for a larger range of values for layer diameterD₁.

During sputter etching of pasting disk 400, the base 402 is alsosputtered and base material may deposit on the edge ring 103 and otherchamber surfaces and components. Since the base material is a dielectricor highly resistive material, deposited base material will tend to leavethe dielectric properties of the edge ring 103 and other chambercomponents unaffected so that there is no undesirable shift in thesputter etch process. However, multiple pasting treatments of chamber100 may result in a build up of conductive pasting material on the base402 due to the pasting material which follows blocked ejectiontrajectories 505 and deposits on the base top surface 406. The build upof conductive pasting material on the base 402 may effectively reducethe edge exclusion width 410 of pasting disk 400 which may causeundesirable deposition of conductive pasting material on edge ring 103during pasting treatment. The pasting disk 400 may therefore beperiodically replaced or cleaned to keep the edge exclusion zone 403free of pasting material and prevent undesirable deposition of pastingmaterial on edge ring 103. Additionally, the pasting disk 400 may haveto be periodically replaced due to the depletion of pasting materialafter multiple pasting treatments.

FIG. 5B is a cross sectional view of another embodiment of a pastingdisk 400 and edge ring 103 according to the present invention. Thepasting material layer 401 has a layer diameter D_(1B) and the base 402has a base diameter D_(2B). The edge ring 103 has a differentcross-sectional profile which lowers the top surface 140A relative tothe base top surface 406 and limit distance d is increased. For thepurpose of comparison, the pedestal 107 dimensions, base diameterD_(2A), and layer and base thicknesses T₁,T₂ remain unchanged from FIG.5A, and D_(2A)=D_(2B). Note that the increased limit distance d allows alarger layer diameter D_(1B) (and smaller edge exclusion width 410) sothe D_(1B)/D_(2B)>D_(1A)/D_(2A) while still preventing ejectiontrajectories 506 from being intercepted by the top surface 140A of edgering 103. As FIGS. 5A and 5B show, the required edge exclusion width 410necessary to prevent the deposition of sputtered conductive material onedge ring 103 is dependent in part on the locations of various featureson the edge ring 103.

FIG. 6 is a cross sectional schematic view of the upper portion of thechamber 100 shown in FIG. 1 according to one embodiment of theinvention. The pasting disk 400 is disposed on pedestal 107 which is inthe processing position. The layer top surface 404 of the pastingmaterial layer 401 is a distance H from top interior surface 122A ofdome 104. The pasting material layer 401 has layer diameter D_(1A)measured to edge surface 607A. An impact point 601A may be located atlayer top surface 404 and edge surface 607A and receives ions duringsputter etching. Conductive material is ejected from impact point 601Athrough a dispersion angle γ and travels in line-of-sight trajectoriesalong ejection trajectories 603A (solid arrows) and impacts variousinterior surfaces of chamber 100, such as top interior surface 122A,sidewall interior surface 122B, and walls 121 of deposition shields 105where the conductive material may deposit during the pasting process.Some of the ejected conductive material may travel along one ejectiontrajectory 603A and deposit at point 605A on sidewall interior surface122B of dome 104.

For clarity, only two line-of-sight ejection trajectories 603A are shownfor impact point 601A, but many line-of-sight ejection trajectories 603Amay be possible for impact point 601A as indicated by dispersion angle γwhich represents a range of directions for line-of-sight ejectiontrajectories 603A. Additionally, dispersion angle γ is only half of afull dispersion angle 2γ which represents a full range of possibledirections (in two dimensions) for line-of-sight ejection trajectories603A about impact point 601A. The full dispersion angle 2γ may rangefrom 0 degrees to 180 degrees or more depending on the location of theion impact point relative to the edge surface 607A of the pastingmaterial layer 401.

A second impact point 601B is shown in FIG. 6 for the case when pastingmaterial layer 401 has a larger layer diameter D_(1B) measured to edgesurface 607B. Conductive material is ejected from impact point 601Bthrough a dispersion angle γ and travels in line-of-sight trajectoriesalong ejection trajectories 603B (dashed arrows). For comparison, theimpact point 601B has the same location as 601A relative to pastingmaterial layer 401, and only ejection trajectories 603B parallel toejection trajectories 603A are shown. Ejected conductive pastingmaterial travels along one ejection trajectory 603B and deposits atpoint 605B on sidewall interior surface 122B. Note that the increasefrom layer diameter D_(1A) to layer diameter D_(1B) of pasting materiallayer 401 lowers the ejection trajectory 603B so that point 605B isbelow point 605A at sidewall interior surface 122B by a distance X, andso a larger interior surface area of the dome 104 and chamber 100 may bemore effectively covered by pasting material during the pasting processby increasing the diameter of the pasting material layer 401 on pastingdisk 400.

FIG. 6 also shows that ejection trajectory 603A could be lowered topoint 605B by increasing the distance H from layer top surface 404 totop interior surface 122A of dome 104, and so increasing the distance Hmay also increase the deposition coverage area of pasting material oninterior surfaces of the dome 104. However, the distance H is determinedin part by the dome 104 geometry and the requirements of plasma 102proximity to layer top surface 404 during sputter etching, and so theadjustability in the value of distance H during the pasting process maybe limited.

Since it is usually desirable to increase the area of pasting coveragefor chamber 100 surfaces which are disposed near or over the substrate101 to reduce the risk of particle contamination, the layer diameter D₁of pasting disk 400 may be selected to have a value which provides alarge pasting coverage area while still preventing or minimizing thedeposition of pasting material on edge ring 103. To further facilitatethe pasting treatment process, the pasting disk 400 may be suitablysized and shaped for transfer to and from chamber 100 using a substratehandling robot (not shown). Additionally, the chamber 100 may bemodified so that the pasting disk 400 may remain within the chamber 100during substrate 101 processing.

FIG. 7A is a schematic cross sectional top view of another embodiment ofthe chamber shown in FIG. 1. Chamber 100 may be suitably adapted toinclude a shutter apparatus 700 which includes a shutter arm housing701, shutter arm 702, and shutter arm shaft 703. The shutter arm housing701 is coupled to chamber body 106 so that a vacuum seal exists betweenthe shutter arm housing 701 and chamber body 106. The shutter arm 702 iscoupled to a shutter arm shaft 703 so that the shutter arm 702 mayrotate between housing position A and chamber position B. A rotaryactuator (not shown) or other suitable means may be coupled to one endof the shutter arm shaft 703 to cause the shutter arm 702 to rotatebetween housing position A and chamber position B. The shutter arm 702is suitably adapted to receive and support pasting disk 400 so that thepasting disk 400 may be transferred to and from lift pins 109 (see FIG.7B).

FIG. 7B is a schematic cross sectional view of the chamber shown in FIG.7A. During substrate 101 processing, the shutter arm 702 supportspasting disk 400 at housing position A inside shutter arm housing 701.After substrate 101 processing, the substrate support 124 is lowered bylift mechanism 113 to a transfer position. The substrate lift 130 maythen raise platform 108 and lift pin 109 so that lift pins 109 contactthe substrate 101 and lift the substrate 101 from pedestal 107 so that asubstrate handling robot blade (not shown) may enter chamber 100 andmove under the substrate 101. The substrate lift 130 may then lowerslightly to an exchange position so that the substrate 101 istransferred from lift pins 109 to the substrate handling robot blade.The substrate handling robot blade can then remove the substrate 101from chamber 100.

To prepare for a pasting treatment, the shutter arm 702 may then rotateto chamber position B (see FIG. 7A) so that the pasting disk 400 isabove lift pins 109. The substrate lift 130 may then raise slightly toan exchange position so that the pasting disk 400 is transferred fromshutter arm 702 to lift pins 109. The shutter arm 702 may then rotateback to housing position A, and the substrate lift 130 can then movedownwards so that the pasting disk 400 is transferred from lift pins 109to pedestal 107. After the pasting disk 400 has been transferred to thepedestal 107, the substrate support 124 may move upwards to processingposition so that pasting disk 400 is in processing volume 119 andpasting treatment may begin.

After the pasting disk 400 has been sputter etched and the pastingtreatment is completed, the pasting disk 400 may be transferred back tothe shutter arm 702 by reversing the aforementioned steps. The sequenceand manner of steps for transferring pasting disk 400 to and fromshutter arm 702 and pedestal 107 and described herein are not meant tobe limiting, and other embodiments for said steps may be contemplatedfor the present invention.

FIG. 7C is a schematic cross sectional view of another embodiment of thechamber shown in FIG. 7B. In addition to not having to remove thepasting disk 400 from the chamber 100, the shutter apparatus 700 has anadditional advantage of allowing the use of a pasting disk 400 that islarger in diameter than substrate 101 which is transferred by asubstrate handling robot. The shutter arm 702 may be suitably adapted tosupport and transfer a pasting disk 400 which has a base diameter D₂which is larger than the diameter of the substrate 101. The location oftop surface 140A of the edge ring 103 may also be adapted so that thepasting disk 400 may rest on pedestal 107 without interfering with theedge ring 103, as shown in FIG. 7C. The base diameter D₂ may be sized toexceed the diameter of the substrate 101 so that all or at least part ofthe top surface 140A of the edge ring 103 is covered by the base 402during the pasting process to prevent or minimize deposition of pastingmaterial onto the edge ring 103. It is to be understood that top surface140A may comprise one or more surfaces of the edge ring 103 whichgenerally face the processing region 119.

FIG. 7D is a schematic top view of the dielectric ring and pasting diskshown in FIG. 7C. The edge ring 103 has edge ring inner diameter D_(i)measured to inner surface 140E (dashed line) and edge ring outerdiameter D_(o) measured to outer surface 140D. The pasting disk 400 hasbase diameter D₂ and layer diameter D₁, and the base 402 covers part ofthe edge ring 103 top surface 140A. In another embodiment, base diameterD₂ is approximately equal to edge ring outer diameter D_(o) and the base402 completely covers the edge ring 103.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

The invention claimed is:
 1. A method for depositing pasting material ina plasma processing chamber, comprising the steps of: providing apasting disk having a pasting material layer and a base in a plasmaprocessing chamber, wherein a ratio of a diameter of the pastingmaterial layer to a diameter of the base is selected to reduce pastingmaterial deposition onto a dielectric edge ring disposed in the plasmaprocessing chamber, wherein the ratio of the diameter of the pastingmaterial layer to the diameter of the base ranges from about 0.4 toabout 0.98; transferring the pasting disk from a pasting disk handlingdevice to a substrate support pedestal disposed in the plasma processingchamber; positioning the pedestal to a processing position; sputteretching the pasting material layer to deposit pasting material ontoplasma processing chamber surfaces, wherein this step is performed withno substrate in the plasma processing chamber; positioning the pedestalto a transfer position; and transferring the pasting disk from thesubstrate support pedestal to a pasting disk handling device.
 2. Themethod of claim 1, wherein the pasting disk handling device is asubstrate handling robot.
 3. The method of claim 1, wherein the pastingdisk handling device is a shutter arm.
 4. The method of claim 1, whereinthe ratio of the layer diameter to the base diameter ranges from about0.7 to about 0.98.
 5. The method of claim 1, wherein the pastingmaterial layer comprises an electrically conductive material.
 6. Themethod of claim 1, wherein the base diameter is selected to cover atleast part of the dielectric edge ring.
 7. The method of claim 1,wherein the pasting material layer is aluminum, copper, silver, or gold.8. The method of claim 1, wherein the base is a dielectric or highresistivity material.
 9. The method of claim 1, wherein the bass is atleast one of quartz, aluminum oxide (Al₂O₃), silicon (e.g., intrinsicsilicon), silicon oxide (e.g., SiO₂) or ceramic.
 10. The method of claim1, wherein the pasting material layer comprises non-conductive orelectrically insulative materials.
 11. The method of claim 1, whereinthe pasting material layer has a thickness between about 1 micron (μm)and about 100 microns (μm).
 12. The method of claim 1, wherein the basehas a thickness between about 0.5 millimeters (mm) and about 5millimeters (mm).
 13. The method of claim 1, wherein transferring thepasting disk from the substrate support pedestal to the pasting diskhandling device further comprises: transferring a substrate onto thesubstrate support pedestal for processing while maintaining the pastingdisk in a shutter arm housing.
 14. The method of claim 13, wherein thepasting disk is maintained on a shutter arm disposed in the shutter armhousing connected to the plasma processing chamber.
 15. The method ofclaim 1, wherein the pasting disk has an edge portion rest on a topsurface of the dielectric edge ring.
 16. The method of claim 1, whereinthe pasting disk has a pasting disk edge facing an inner side-wallsurface of the dielectric edge ring.